Water heater



FIG. 1 is a front view thereof;

FIG. 2 is a rear view thereof;

FIG. 3 is a left side view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a top view thereof;

FIG. 6 is a bottom view thereof; and,

FIG. 7 is a perspective view thereof.

The broken lines shown in the figures illustrate portions of the water heater that do not form part of the claimed design. 

CLAIM The ornamental design for a water heater, as shown and described. 